System of rotating wings controlled by an automatic rudder



July 24, 1934. g. SERRAGLI 9 2 SYSTEM OF ROTATING WINGS CONTROLLED BY ANAUTOMATIC RUDDER Filed July 20, 1935 15 lNvENT'oR GIOVANNI SER AGLI BY[yd/$1 AM; 0-. ATTORNEYS.

meted July 24, 1934' UNITED STATES SYSTEM OF R T A T IN G WINGS CON-TROLLED BY AN AUTOMATIC RUDDER Giovanni Serragli, Florence, ItalyApplication July 20, 1933, Serial No. 681,234 In Italy August 22, 1932 6Claims. (01. 244-19) The object or the present inventionis a system ofrotating wings or gyroplane which may be utilized as an autogyroplane,but which in the ordinary flight conditions, may be arrested thus Iproducing only a small aerodynamic effect which is not detrimental tothe penetration of the aircraft on which it is applied.

The general object above mentioned is obtained in this case in anautomatic manner by means of a small rudder connected to one of theblades of the propeller. In addition, its mounting on the aircraft ismade in accordance with such principles that ensure the best possibleaerodynamical eflect, eliminating at the same time the disadvantage tothe stability thatthe aircraft would be liable to receive owing to theaction of the gyroplane.

In the drawing:

Fig. 1 shows the propeller in plan,

Figures 2 and 3 show details of the automatic rudder, and v Figs. 4 and5 the arrangement of the end view and in plan respectively.

The gyroplane comprises four blades 1, 2, 3, 4

(Fig. 1) which however could be reduced to two only (2-4) All the bladeshave their angles or connection to the hub very small, this being anecessary characteristic for ensuring satisfactory working;- the saidangle may however be slightly varied along the radius.

The blades 1 and 3 are equal b'oth in their form and lengths, and areslightly tapered towards their outer ends. The blades 2 and 4 differ onthe contrary from each other, blade 2 being substantially shorter, widerand thicker than blade 4 (Fig. 1), 2 and 4 forming together a singleunit which ,onits whole has a good aerodynamical penetration, theirdimensions being selected in such a way as to realize the so calledstreamline form, while maintaining the blade form. By providing suitablecounterweights inside the'blades, the necessary coincidence of thecentre of gravity with the axis of rotation of the propeller isobtained, or the solid end of the blade 2 may be made with wood (asshown) and the rest may be made hollow.

The blade 4 is provided with the automatic rudder 5consisting of a smallflat piece, having a rectangular or trapezoidal rounded shape 5' inplan, or any other form. Its dimensions may be varied greatly. Therudder 5 may also be very large, in which case the size of blade 4 towhich it is connected may be proportionately reduced; it would also bepossible to eliminate this latter parts, in

sliding movement is thus prevented.

Fig. 3 shows the section of the flat piece 5 (hatched section) and thatof the blade 4 (nothatchedsection). As shown, the angle 01' connectionof the blade to the hub is small. The small flat piece 5 can rotatefreely round-tile shaft 6 but its movement is limited by suitableprojections or stop teeth (not shown) to two extreme positions, whichare the following:

(1) The small flat piece 5 assumes the same inclination or angle ofincidence as the blade 4 (viz; a very small angle). In this case itconstitutes a continuation of blade 4 so that the two sections (hatchedand not hatched) shown in Fig. 3 would be superposed.

(2) The small flat piece 5 assumes the position indicated in'Fig. 3, oran angle of incidence a from 10 to 30 with respect to the section of theblade-4 (not hatched section) more or less, according to cases;

As already explained, the piece 5 may oscillate freely between the twolimiting positions above said, but on reaching said positions it isstopped by projections or stop teeth, which are not shown in the figure,but which can easily be provided. 1

Inside the blade 4 a small bolt or movable stop tooth 8 is alsoprovided, which includes a small mass 9. This bolt or stop tooth slidesin suitable guides and can enter a recess 10 provided in the flat piece5 when this latter is in the first limiting position above described,forming a body with the blade 4; in this position the bolt 8 preventsabsolutely the rotation of the piece 5 round the, spindle 6. Normallyhowever, the bolt is kept retracted and is maintained completely withinthe blade 4 by means of a small spring 11 as shown in Fig. 2.

The gyroplane is mounted on the aircraft and kept in position by meansof four stays 12, 13, 14, 15 (Figs. 4 and 5) consisting of hollow tubesmade of steel or of other suitable materials. These stays are arrangedcrosswise, as shown in the viewof Fig. 5, where areseen in plan thepoints of junction oi the tubes on the fuselage of the aircraft, thearrow 16 indicating the direction of advancement of the aircraft whichcorresponds also to its traction axis.

The stays or tubes are united at their upper ends (Fig. 4 shows only thestays 12 and 14 for clearness) and carry a horizontal pivot 17 roundwhich the axis of rotation 00 of the gryoplane can rotate. This axis ismaterially formed with a tube which is flattened at its lower end,forming a fiat head 18 which can slide into a curved metal guide 19 theends of which are connected directly to the stays 12 and 14respectively, and indirectly by means of the connecting rods 20-21 to1'3 and 15 respectively.

To the end of the flattened head 18 which extends below the guide 19 toa convenient point, two metallic cables 22-23 are fixed, which can beunited by means of suitable pulleys, to one single control cable withineasy reach of the pilot who is thus enabled to regulate the inclinationof the axis of rotation of the propeller between the two extremepositions previously mentioned, viz to the position (1) in which casethe axis of the propeller is normal to the axis of the fuselage of theaircraft, and to the (2) position when the said axis is inclinedrearward from 30 to 40 in which case the tube 00 rests on the stay 12.

The device is placed at such a depth that the centre of gravity of theaircraft on which the gyroplane is applied (generally an aeroplane) ispositioned within the angle formed by the two directions of the axis ofrotation indicated by' the positions (1) and (2) above mentioned, andwhich is shown approximately by the point G, in Fig. 4. The device,comprising the stays 12 1e and the other parts, described above isenclosed in a suitable casing 24 (shown by the dotted line in Fig. 5) soas to produce a sector having a stream line shape, adapted to increasethe aerodynamical penetration of the whole device. The sector comprisesthe pivot 17 as well as the whole triangle having as sides 121 l up tothe dorsal line m-m of the fuselage. The stays 1315 and the rods 20-.-21are provided with the usual aerodynamical casings.

The device, as far as it relates to its installation on the aircraft inthe transverse direction, is disposed in such a way that the gyroplane,both for the displacement of its whole unit and for the differentlengths assigned to the rods 20 and 21, is placed slightly to the rightor to the left of the traction axis of the aircraft (viewed from thetop) according to whether the gyroplane rotates anti-clockwise orclockwise. If the gyroplane rotates in the direction indicated by thearrow 25 (Fig. 1) its mounting on the aircraft must be made slightly tothe right as shown in Fig. 5. If the rotation occurs in the oppositedirection, the mounting must be made slightly to the left.

With regard to the disposition of the various controls etc. any knownmechanical means may be used, which is not shown on the drawing.

It is preferable to insert buffers at the points marked 2627 on Fig. 5in order to reduce the shock due to the impact of the head piece 18.

The working of the device is as follows:

When the gyroplane is in the position above described (as shown on Fig.4) viz with its axis perpendicular, or nearly perpendicular to thefuselage, the rudder 5 has the effect of causing it to shift in theposition shown in Fig. 1; viz the gyroplane assumes the form of a smallaeroplane having as fuselage 24 and 1-3 as wings.

The section of the fiat piece 5, or other equivalent member. oossessesthe known aerodynamical characteristic of having the centre of pressuredisposed in advance to the centre of the said section, so that if theplane 5 (Fig. 3) is struck by the lateral wind 28 from the right, or 29from the left, the resultants from the aerodynamical effect 30 or 31respectively, are always placed in advance of the centre of the spindle6 so that in any case the small plane is fixed by the relative momentsin the position described under the end position marked 2, correspondingto that shown on Fig. 3, so that it is pressed in any case against therelative stop tooth. Under this condition the fiat piece 5 acts as avertical rudder, and as such, it causes a lateral dynamical effect whichtends always to stabilize the propeller in the position shown in Fig. l,viz with the axis 2-4 parallel to the direction of advancement V. Thiseffect has been claimed and is covered by the United States Patent No.1,811,867 granted to the same applicant. The gyroplane works thus as asmall fixed surface which does not cause any disturbance to the normaladvancement of the airplane.

Supposing now that the trajectory of the airplane becomes inclineddownwards, which occurrence may be caused either by. the fall of theapparatus, or by the pilot causing it to descend with a steep gradient(with the inclination control), it is easy to see in this case that whenthe said inclination has reached a certain value, the aerodynamicaleffect on the piece 5 ceases to be lateral, as shown by the arrows 28and 29 in Fig. 3, but the rudder is struck from below in the directionindicated by the arrow 31. In these conditions the flat piece 5straightens itself automatically, assuming the position described aboveunder (1) viz forming one single body or a continuation of the blade 1.In these conditions the rudder effect of the piece 5 ceases to beoperative, and the system becomes a very effective self rotatingpropeller which gives a very substantial braking action. In order toensure that during the said auto-rotation the plane 5 remains in thedesired position, the spring 11 provided on the bolt placed into theblade P4 is adjusted so that .it

becomes depressed by the centrifugal force after a certain number ofrevolutions, allowing the bolt 8 to enter the recess 10, thus forming arigid connection between the rudder 5 and the blade 4.

When the trajectory of the aircraft ceases to be inclined, on theapparatus resuming its horizontal flight, the propeller decreases itsspeed of rotation and the action of the spring prevails again againstthe effect of the centrifugal force; this has the effect of retractingthe bolt inside the blade 4 thus releasing the fiat piece 5 which underthe action of the lateral wind (28 or 29) resumes its position as shownin Fig. 3 in which it operates as a vertical rudder, stabilizing againthe gyroplane in the position shown in Fig. 1 as heretofore described.

The rudder ensures, in the manner above de-.

scribed, the automatic change from the fixed propeller trim to theautorotation trim and conversely without any intervention on the part ofthe pilot, who may eventually be called only to regulate the inclinationof axis 0. 0.

The position of the installation in relation to the centre of gravity Gis effected as shown on Fig. 4, as it is convenient and self evidentthat the gyroplane, when in its autorotating phase, should give rise toa couple that tends to lift up the apparatus (anti-reversing couple)which is advantageous on landing for opposing often occurring contraryactions which are dangerous to safety. The side displacement is in thedirection indicated on Fig; 5 as a self rotating propeller does notpossess generally a centre of pressure coinciding with the axis ofrotation; the said centre being placed slightly to the right or to theit may happen that in certain conditions of work-' ing they may produceinconveniences due to vibrations, owing to the different moment ofthrust they transmit to the hub of the propeller. This inconvenience maybe overcome by setting the blade 4 (the longer blade) with an angle ofincidence greater than that of blade 2 (the shorter blade). Thus theincidence of'the blade 4 becomes reduc d, as well as its aerodynamicaleffect, which latter, through suitable calculations, may be made equalto that of blade 2 thus ensuring the necessary balance.

The control for the inclination of the axis 0-0 operates in a mannerwhich need not be explained in detail. It will only be sufficient toexplain in thisconnection that it is preferable to use a rope controlinstead of any rigid control, in order to eliminate all vibrations.

The pilot may use with advantage the gyroplane in auto-rotation when anexceptional value of the lift becomes necessary, as also in the case oftaking off, of landing, or in flying at ,slow velocity.

I claim:

1. System of rotating wings for the aerodynamical braking of aircraftduring their descent, or in all cases when an-additional support-isrequired, an axle, said system being mounted loose on said axle which isin ordinary conditions perpendicular to the axis of the fuselage of theaircraft, formed with four blades or wings mounted on to the axle with avery small or null angle of incidence, two of said blades or wings beingequal to each other, and having a slightly decreasing width towardstheir outer ends, the other two blades or wings being of differentlengths, width and thickness, one being wider, shorter, and thicker withrespect to the other, forming together a body having agood aerodynamicalpenetration; an automatic rudder being provided at the outer end of thelonger blade formed with a fiat plate the inclination of which isvariable, this flat plate acting as a vertical rudder when the directionof the advancement of the aircraft lies in the plane of rotation of theblades, but ceasing to act as such when the trajectory-of the aircraftinclines downwards, either owing to the fall or to a voluntary steepgradient of descent.

2. System of rotating wing according to claim 1, in which thecsmallautomatic rudder adiusts itself in the preferred position, and means tolock the rudder in adjusted position, consisting of a tooth or boltactuated by centrifugal force. I 3.v System of rotating wings for theaerodynamical braking of aircraft during the descent thereof, or in allcases when an additional support isrequlred, axle, said system beingloosely ;-=m'o unted-on said axle which has a hub and is in .ordiiiar'yconditlons perpendicular to the axis of I 1 the fuselage of theaircraft, formed with four blades or wings mounted on the hub with avery small or null angle of incidence, of .which blades or wings two areequal to each other, while the other two blades or wings are ofdifferent length, width and thickness, one of the latter being wider,shorter, and thicker than the other, an automatic rudder provided at theend of the longer blade and formed with a flat piece having a variableinclination and which acts as a vertical rudder when the direction ofadvancement of theaircraft coincides with the plane of rotation of theblades, but ceases to act as such when the trajectory of the aircraftinclines downwards, whereupon said automatic rudder adjusts itself andis automatically locked in predetermined position, the axle on which therotating wings are loosely mounted being both adapted to rotate round ahorizontal pivot supported by four stays fixed on the fuselage of theaircraft, and enclosed in a casing having an aerodynamical outline, therotation of said axle being controlled by the pilot by means of metalliccables, while the inclination of the axis of rotation'is made to varyfrom naught to 30 and even to 40 degrees.

4. System according to claim 3, wherein the rotating wing device whichincludes the axle with its hub and the wings or blades as well as thesmall automatic rudder, is mounted on the fuselage so that the centre ofgravity of the aircraft both is comprised within the angle formed by thetwo extreme limiting positions of the rotating wing, viz from 0 to30-40, and is in addition displaced slightly to the right or to theleft, so that the centre of the aerodynamical pressure of the wing maycoincide with the axis of thrust of the aircraft.

5. System according to claim 3 wherein the two blades having differentlength, width and thickness are mounted on the hub with different anglesof incidence, in order to transmit thrusts of substantially equalintensity to said hub.

,6. System of rotating wings for the aerodynamical braking of aircraftduring the descent thereof, and in all cases when an additional supportis required, an axle on which said system is loosely mounted said axleprovided with a hub and in normal conditions disposed perpendicular tothe axis of the fuselage of the aircraft, and which system is formedwith four blades or wings connected to said hub with a very small ornull angle of incidence, of which blades or wingstwo are both oppositeand equal to each other, while the other two blades or wings are ofdifferent length and width and one .of the latter being wider andshorter than the other, which blades or wings together form an efficientaerodynamic body, an automatically operating rudder pivotally mounted atthe outer end of the longer of said two different blades or wings andformed with .a practically flat plate adapted to be inclined at variousangles, which flat plate acts as a vertical rudder when the direction ofthe advancement of the aircraft practically coincides with the plane ofrotation of the blades, but ceases to act as a rudder when thetrajectory of the aircraft for any reason inclines downward, andcentrifugally operated automatic means locking said plate inpredetermined'hligned position with respect to said longer blade orwingduring such rotation of said blades or wings.

GIOVANNI SERRAGLI.

